1. Field of the Invention
This invention relates to fabric laminates having excellent ballistic resistant properties as well as superior resistance to penetration of fragments, such as shrapnel. More particularly, the invention pertains to a light-weight, flexible, non-woven, fragment and ballistic resistant material formed from high-strength polymeric fibers in an elastomeric matrix.
2. Description of the Related Art
Ballistic resistant articles containing high strength fibers that have excellent properties against deformable projectiles are known. Articles such as bulletproof vests, helmets and structural members of military equipment, are typically made from fabrics comprising such high strength fibers. Fibers conventionally used include polyethylene fibers, para-aramid fibers such as poly(phenylenediamine terephthalamide), graphite fibers, nylon fibers, glass fibers and the like. For many applications, such as vests or parts of vests, the fibers may be used in a woven or knitted fabric. For many of the other applications, the fibers are encapsulated or embedded in a composite material to form either rigid or flexible fabrics.
Various ballistic resistant constructions are known that are useful for the formation of articles such as helmets, panels and vests. For example, U.S. Pat. Nos. 4,403,012, 4,457,985, 4,613,535, 4,623,574, 4,650,710, 4,737,402, 4,748,064, 5,552,208, 5,587,230, 6,642,159, 6,841,492, 6,846,758, all of which are incorporated herein by reference, describe ballistic resistant composites which include high strength fibers made from materials such as extended chain ultra-high molecular weight polyethylene. These composites display varying degrees of resistance to penetration by high speed impact from projectiles such as bullets, shells, shrapnel and the like.
U.S. Pat. Nos. 4,403,012 and 4,457,985 disclose ballistic-resistant composite articles comprised of networks of high molecular weight polyethylene or polypropylene fibers, and matrices composed of olefin polymers and copolymers, unsaturated polyesters, epoxies, and other polymers moldable below the melting point of the fiber. U.S. Pat. Nos. 4,623,574 and 4,748,064 disclose simple composite structures comprising high strength fibers embedded in an elastomeric matrix. U.S. Pat. Nos. 4,737,402 and 4,613,535 disclose complex rigid composite articles having good impact resistance which comprise a network of high strength fibers such as the ultra-high molecular weight polyethylene and polypropylene disclosed in U.S. Pat. No. 4,413,110, also incorporated herein by reference, embedded in an elastomeric matrix material and at least one additional rigid layer on a major surface of the fibers in the matrix. U.S. Pat. No. 4,650,710 discloses a flexible article of manufacture comprising a plurality of flexible layers comprised of high strength, extended chain polyolefin (ECP) fibers. The fibers of the network are coated with a low modulus elastomeric material.
U.S. Pat. Nos. 5,552,208 and 5,587,230 disclose an article and method for making an article comprising at least one network of high strength fibers and a matrix composition that includes a vinyl ester and diallyl phthalate. U.S. Pat. No. 6,642,159 discloses an impact resistant rigid composite having a plurality of fibrous layers which comprise a network of filaments disposed in a matrix, with elastomeric layers there between. The composite is bonded to a hard plate to increase protection against armor piercing projectiles. U.S. Pat. No. 6,841,492 discloses bi-directional and multi-axial fabrics, fabric composites, ballistically resistant assemblies thereof and the methods by which they are made. The fabrics are comprised of sets of strong, substantially parallel, unidirectional yarns lying in parallel planes, one above the other. U.S. Pat. No. 6,846,758 discloses woven fabric laminates having superior resistance to penetration by ballistic projectiles. Laminates of the invention are comprised of a fabric woven from a high strength, high modulus yarn, a surface coating of a low modulus elastomer and a plastic film bonded to its elastomer-coated surface.
One problem associated with the current ballistic resistant fabrics and articles is their limited resistance to the penetration of fragments, such as shrapnel. The present invention provides a solution to this problem. It has been unexpectedly found that a non-woven fabric formed from a consolidated network of high-strength fibers consolidated with from about 7% to about 15% by weight of an elastomeric matrix composition, and in combination with protective layers of a polymer film on each surface of the fabric, achieves a significant improvement in fragment resistance compared to fabrics of the prior art, while also maintaining excellent properties against deformable projectiles.